Method of using a direct sequence spread spectrum in vehicle location approximation when using orthogonal frequency-division multiplexing

1. A method of using a direct sequence spread spectrum (DSSS) in vehicle location approximation when using orthogonal frequency-division multiplexing (OFDM) comprises the steps of: (A) providing an orthogonal frequency-division multiplexing (OFDM) device, wherein the OFDM device comprises a wireless terminal and a multiple-input and multiple-output (MIMO) antenna; (B) encoding a pilot uplink signal through a channel encoding module of the OFDM device, wherein the pilot uplink signal is encoded as a direct-sequence spread spectrum (DSSS); (C) transmitting the pilot uplink signal from the wireless terminal to at least one intended target, wherein the at least one intended target is within an operational range of the MIMO antenna; (D)receiving an ambient signal at the wireless terminal, wherein the ambient signal comprises a reflected-pilot uplink signal generated when the pilot uplink signal contacts the at least one intended target; (E) filtering out the reflected-pilot uplink signal from the ambient signal through the OFDM device, wherein the reflected-pilot uplink signal is encoded as a DSSS; (F) decoding the DSSS of the reflected-pilot uplink signal through a channel decoding module the OFDM device; and (G) deriving a location approximation for the at least one intended target through the OFDM device, wherein the location approximation is derived from a matching time delay between the pilot uplink signal and the reflected-pilot uplink signal calculated by the OFDM device, and a direction of arrival (DOA) of the ambient signal derived through the MIMO antenna.

2. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 further comprises: providing the OFDM device with a pseudo-noise (PN) sequence generator; modulating the pilot uplink signal as a PN sequence through the PN sequence generator; demodulating the reflected-pilot uplink signal as a PN sequence through the PN sequence generator; and measuring the time delay between the pilot uplink signal and the reflected-pilot uplink signal as a PN period shift through the OFDM device.

3. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 further comprises the steps of: providing the OFDM device with a match-filtering unit and a rake receiver; transferring the ambient signal through the match-filtering unit and the rake receiver; determining the DOA by filtering out a downlink signal of the ambient signal through the match-filtering unit; calculating the matching time delay by autocorrelating the pilot uplink signal and the reflected-pilot uplink signal at the rake receiver through the DSSS; and displaying an autocorrelation output for the matching time delay through the OFDM device, wherein the autocorrelation output corresponds to the at least one intended target.

4. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 further comprises the steps of: providing the OFDM device with a signal generator unit; adding a cyclic prefix to the pilot uplink signal through a cyclic extension process of the signal generator unit; and removing the cyclic prefix of the reflected-pilot uplink signal through the cyclic extension process of the signal generator unit.

5. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 further comprises the steps of: providing the OFDM device with a radar processor; calculating the matching time delay between the pilot uplink signal and the reflected-pilot uplink signal through the OFDM device; deriving the DOA for the ambient signal through the MIMO antenna; and deriving the location approximation for the at least one intended target by through the radar processor, wherein the matching time delay and the DOA of the ambient signal are inputs to the radar processor.

6. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 , wherein the ambient signal further comprises a downlink signal and a plurality of echo signals, wherein the plurality of echo signals is generated when the pilot uplink signal is reflected from the at least one intended target onto a plurality of target-surrounding objects and off the plurality of target-surrounding objects.

7. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 further comprises the steps of: wherein the at least one intended target is a plurality of targets; and receiving a corresponding reflected-pilot uplink signal from each of the plurality of targets.

8. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 , wherein the pilot uplink signal is transmitted via beamforming.

9. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 , wherein the reflected-pilot uplink signal is received via beamforming.

10. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 , wherein the MIMO antenna is an antenna array.

11. The method of using a DSSS in vehicle location approximation when using OFDM as claimed in claim 1 , wherein the pilot uplink signal comprises a plurality of subcarriers.